The present invention relates to a medical instrument for dissecting tissue in the human or animal body, having an elongated shaft and having at the distal end of the shaft two jaw parts that are movable relative to one another and that coact cuttingly and/or graspingly, at least one of the jaw parts being configured as an electrode which can be impinged upon by high-frequency current.
xe2x80x9cDissectingxe2x80x9d for the purposes of the present invention is understood to mean the cutting of tissue and/or grasping or gripping of tissue in order to cut of f tissue in the body and remove it or set it aside.
An instrument of this kind is preferably used in minimally invasive surgery in which, in contrast to conventional open surgery, the instrument is guided from outside through a small incision into the surgical area, the surgical procedure being performed under endoscopic monitoring.
In such an instrument, often not only is the purely mechanical effect of the jaw parts used to cut off or cut through tissue, but the jaw parts or at least one of the jaw parts can additionally be impinged upon by monopolar high-frequency current so as on the one hand to enhance the cutting effect by way of the thermal effect of the high-frequency current in the tissue, and on the other hand to bring about coagulation of the tissue at the cutting point generating heat , so as to reduce or even eliminate the bleeding that occurs when the tissue is cut through.
While at first only the dissection of smaller portions of tissue could be performed successfully in minimally invasive surgery, the development of minimally invasive surgery is now moving toward removing even larger portions of tissue, for example the large intestine or organs. When removing larger portions of tissue, it is also necessary to cut through larger tissue bridges, which moreover may contain larger vessels. The more severe bleeding that possibly occurs in this context cannot be managed, however, with the monopolar-mode instrument, so that it is additionally necessary, when cutting through larger tissue bridges, to use bipolar-mode coagulation instruments.
This means, however, that while dissecting (i.e. in order to cut through such larger tissue bridges), the surgeon must make an instrument change several times if he or she does not was to rely only on the lesser coagulating effect of the monopolar-mode instrument. The operation thus proceeds in such a way that the surgeon removes tissue principally with the monopolar-mode instrument and, when he or she arrives at a tissue bridge containing a larger vessel, must remove the monopolar-mode cutting instrument from the patient""s body and bring to the operating location a bipolar-mode coagulation instrument. This instrument change is, however, cumbersome, extends the length of the procedure quite considerably in some cases, and increases the risk of complications.
There is known, from the catalog of the German company styled Karl Storz GmbH and Co., Tuttlingen entitled xe2x80x9cKarl Storz-Endoskope,xe2x80x9d Gynecology volume 2/96, page BI/COA 5/7, a bipolar coagulation instrument that has at the distal end two pairs of jaw parts spaced apart from one another, each pair of which is configured as an electrode that can be impinged upon by high-frequency current. The two jaw part pairs are spaced apart from one another and can therefore be operated as a bipolar electrode arrangement. Arranged between the jaw part pairs is a cutting tool in the form of a scalpel that is selectably movable back and forth. With this instrument, a vessel can be clamped between the two jaw part pairs and coagulated, and then cut through by advancing the cutting tool. This instrument is, however, less suitable for being used principally as a dissecting instrument for cutting through tissue. Instead, the principal function of this instrument is bipolar coagulation.
Instruments similar to this are described in WO 95/15124 and U.S. Pat. No. 5,445,638.
In the case of the known instruments cited above, the cutting effect by way of the displaceable scalpel arranged between the coagulation electrodes is purely mechanical, i.e. with no assistance from high-frequency current. In addition, these cutting devices are predominantly suitable only for cutting through vessels, but not for making longer cuts and also not for grasping.
For the purpose cited initially of dissecting tissue in the human or animal body, in which larger portions of tissue are removed and large tissue bridges need to be cut through for the purpose, an instrument of the kind cited initially is therefore functionally correct, since with such an instrument the cutting through of tissue is to the fore.
It is therefore the object of the invention to develop an instrument of the kind cited initially in such a way that with this instrument even larger portions of tissue, and thus larger tissue bridges containing larger vessels, can be cut through with no risk of excessive bleeding.
According to the present invention this object is achieved by a medical instrument comprising:
an elongated shaft having a distal end;
two jaw parts at said distal end of said shaft, said two jaw parts being movable relative to one another and configured to coact for dissecting said tissue, at least one of said two jaw parts being configured as an electrode which can be impinged upon by high-frequency current,
wherein a further electrode which can be impinged upon by a high-frequency current is provided which can be optionally displaced from a retracted proximal position into a distal position adjacent to said two jaw parts in which position said further electrode forms in coaction with said at least one jaw part configured as an electrode one pole of an electrode arrangement for bipolar coagulation of said tissue.
What is therefore made available according to the present invention is an instrument with which it is possible, while using a monopolar-mode instrument in standard fashion, to dissect tissue by cutting and/or grasping, and if necessary to coagulate very small vessels in conventionally monopolar fashion.
If, however, the surgeon encounters a tissue bridge which appears to contain larger vessels, this tissue bridge can be gripped between the jaw parts and the further electrode by advancing the further electrode into the distal position adjacent to the jaw parts. The at least one jaw part configured as an electrode and the further electrode can then be impinged upon by high-frequency current so that the tissue lying therebetween can be coagulated in bipolar fashion. In other words, the jaw parts form the one electrode pole and the further electrode the second electrode pole. Then, preferably after the further electrode has been slid back into its proximal position, dissection can continue with the jaw parts, either purely mechanically or under the action of monopolar current. The invention thus makes available an instrument operable in monopolar fashion for dissecting tissue, in combination with a selectably or optionally connectable bipolar coagulation device, thus achieving the considerable advantage that an instrument change is not necessary for dissection and for bipolar coagulation, and larger portions of tissue can also be dissected quickly and safely while preventing bleeding.
The underlying object of the invention is thus completely achieved.
In a preferred embodiment, the jaw parts are curved out of a longitudinal axis of the shaft, and the further electrode is arranged on a concave side of the jaw parts.
The advantage of this feature is that when the further electrode is advanced into its distal position, the tissue to be coagulated in bipolar fashion can be securely grasped and held between the jaw parts and the further electrode. The curved configuration of the jaw parts acts in this context as a catch hook and backstop preventing the tissue from escaping laterally as the further electrode is advanced.
In a further preferred embodiment, the further electrode is of planar configuration and has approximately the same width dimension as the two jaw parts.
The advantage here is that larger portions of tissue can be coagulated with only one coagulating operation. Of course it is also possible to coagulate several times, shifting the instrument laterally, if a particularly large tissue bridge containing particularly large vessels needs to be cut through. The jaw parts can be open or closed during bipolar coagulation of the tissue, the effective electrode surface of the jaw parts being increased even further when the jaw parts are in the open position.
In a further preferred embodiment the further electrode forms, with at least one of the jaw parts, a catching space for gripping tissue.
The advantage of this configuration is that even thicker tissue and even thicker vessels can be grasped between the further electrode and the jaw parts.
In a further preferred embodiment, the further electrode, in its retracted position, is received in recessed fashion in the shaft.
The advantage here is that in its retracted position, the further electrode does not impede the dissection of tissue using the two jaw parts (which is what is predominantly to be performed with the instrument), and is slid out of the shaft only as necessary.
In a further preferred embodiment, the further electrode is beveled at its distal end on a side facing toward the jaw parts.
The advantage here is that as the further electrode is advanced, the tissue to be grasped between the jaw parts and the further electrode is prevented from being displaced by the further electrode so that it then cannot be coagulated between the further electrode and the jaw parts. The aforementioned curved configuration of the jaw parts is also particularly advantageous in this context, since the concave side of the jaw parts acts in the manner of a catch hook and backstop as the further electrode is advanced, so that the tissue cannot escape laterally as the further electrode is advanced.
In a further preferred embodiment, the further electrode is of at least partially flexible configuration and describes, when advanced, a trajectory that initially runs approximately in longitudinal direction of the shaft with or without a component turned slightly away from the jaw parts, and before reaching the distal position runs with a component directed toward the jaw parts.
The advantage of the flexible configuration of the electrode is that the electrode, when advanced, describes a curved trajectory as a result of suitable guidance or because of a preload imparted to the electrode, so that the tissue to be coagulated can be more easily gripped during advancement and, in the maximally advanced distal position, can be securely held or clamped between the jaw parts and the further electrode.
In this context, it is preferred in one exemplary embodiment if there is arranged on the shaft a cam bevel onto which a cam bevel configured on the further electrode runs as the further electrode is advanced, thus pressing the further electrode toward the jaw parts in the distal position.
What is advantageously achieved thereby is that the tissue can be held with a greater clamping force between the maximally advanced further electrode and the jaw parts.
In a further preferred exemplary embodiment, a cam bevel is arranged on the shaft so that as the further electrode is advanced, it is first spread away from the jaw parts and, in the distal position, deflects elastically toward the jaw parts.
The advantage of this embodiment is that as it advances, the further electrode can first be advanced in a direction away from the jaw parts, so that in turn even larger portions of tissue can be securely grasped. Because the further electrode elastically deflects, in its distal position, toward the two jaw parts, the grasped tissue is then automatically held securely between the jaw parts and the further electrode for bipolar coagulation.
In a further preferred embodiment, there is arranged at the proximal end of the instrument a handle that has two grip elements for actuation of the jaw parts and a further grip element for actuation of the further electrode, the grip elements forming a grip arrangement operable with one hand.
The advantage of this feature is that actuation of the jaw parts on the one hand, and selectable actuation of the further electrode (i.e. advancing and retracting the further electrode), can be performed particularly conveniently and, above all, by one-handed operation. This improves the handling of the instrument according to the present invention, and makes it possible to work in fatigue-free fashion with the instrument.
It is preferred in this context if the further grip element is joined via a lever arrangement to the further electrode in such a way that by pulling the further grip element, the further electrode is slid from its proximal into its distal position.
This configuration of the further grip element further improves the handling of the instrument, since an actuation of the further grip element by tension in order to advance the further electrode makes possible better apportioning of force and thus more reliable operation with the instrument.
In a further preferred embodiment, the further electrode is preloaded into its proximal position, into which it automatically returns after the further grip element is released.
This feature further improves the handling of the instrument according to the present invention.
In a further preferred embodiment, the further electrode is joined to the further grip element via an actuation element received in axially movable fashion in the shaft, the actuation element furthermore being joined via a wiper contact to a high-frequency current lead-in.
What results therefrom, because of the axially movable actuation element, is on the one hand a particularly advantageous energy transfer between the further grip element and the further electrode, and on the other hand, as a result of the wiper contact, an advantageously physically simple and reliable application of current to the further electrode as a result of the delivery of current through the movable actuation element.
In a preferred embodiment, the wiper contact allows the passage of current to the further electrode only when the electrode has been advanced into or almost into the distal position.
This embodiment advantageously improves the operating reliability of the instrument according to the present invention.
In a further preferred embodiment, the actuation element is joined to the further grip element removably, preferably by snap-locking.
The advantage here is to make possible easy disassembly of the instrument in terms of the coagulation device provided according to the present invention.
In a further preferred embodiment, the jaw parts are removably joined to the grip elements by way of an actuation element received in axially movable fashion in the shaft.
This feature further improves the disassembly capability of the instrument according to the present invention, so that the instrument according to the present invention can easily be cleaned and thus fully satisfies the stringent hygiene requirements in terms of sterility.
It is preferred in this context if the jaw parts are joined to the distal end of the shaft via a bayonet closure.
This configuration of the join between the jaw parts and the shaft creates a configuration that is advantageously easy to operate in order to join the jaw parts to and detach them from the shaft.
It is particularly preferred if the instrument can be disassembled into the subassemblies made up of the jaw parts with the actuation element joined thereto, the further electrode with the further actuation element, the handle, and the shaft.
As a result of this ability of the instrument to be disassembled into the aforesaid four subassemblies, the instrument according to the present invention can be cleaned particularly thoroughly and thus meets the most stringent hygiene requirements.
Further advantages are evident from the description below and the appended drawings.
It is understood that the features recited above and those yet to be explained below can be used not only in the respective combination indicated, but also in other combinations or in isolation, without leaving the context of the present invention.